In iPhone App I want add functionality to (imageview or webview or other control) zoom in/out an image with pinch gesture.
You can use a UIScrollView for that.
Add a UIImageView to the UIScrollViewand configure the UIScrollView for zooming via its propertys. Check the UIScrollview Class Reference - Zooming and Panning Section
Edit:
Good point by Mike: Check the PhotoScrollersample code by Apple, too
Please refer to this code. I have used it in one of my apps so it works:
- (IBAction)handlePinch:(UIPinchGestureRecognizer *)recognizer {
recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
recognizer.scale = 1;
}
Also don't forget to add Pinch gesture recognizer to your imageView.
Hope this helps.
Related
Hi i am new to iOS programming.
I need to create an photo library like iPhone native photo app. I have found a library MWPhotoBrowser
that provides nearly same UI for photo browsing and its perfect for my requirement. But now i have 2 problems
First is that i need to create a grid layout with thumbnails. Clicking on an thumbnail should display image in full screen with browsing functionality. I tried to dynamically adding UIImageViews in UIScrollView, but UIScrollView is not scrolling and images are going out of screen.
Second is i could not get any tap handler on UIImageView so that i can open an image in full screen.
Looking for some tips here, i am really stuck here.
You can give a shot to this library, it has both features which you are looking for.
https://github.com/gdavis/FGallery-iPhone
Hope it helps :)
For ScrollView scrolling issue you have to increase scrlViewMain.contentSize dynamically. Create a for loop and put bellow code at the end of loop.
scrlViewMain.contentSize = CGSizeMake(0, incermentAsPerYourNeed);
For the tapping issue you have to add TapGesture. Put bellow code when your ImageView creates.
imgView.tag = giveAsPerYourRecordsID;
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleImageTap:)];
tap.cancelsTouchesInView = YES;
tap.numberOfTapsRequired = 1;
tap.delegate = self;
[imgView addGestureRecognizer:tap];
[tap release];
And bellow your catch method for tapping.
- (void) handleImageTap:(UIGestureRecognizer *)gestureRecognizer {
UIImageView *tmpImgView = (UIImageView *)gestureRecognizer.view;
}
I have also developed similar functionality a few days ago for my project.
For tap issue you should use UIButton instead of UIImageView, it gives you tap action event. For Scrollview not scrolling, just make sure you update contentSize property of UIScrollView, otherwise it would not scroll according to your subviews.
I have a scrollview and i added the images from webservice. Now i want to add pinch zoom effect to the images. But when i am going to zoom in image becomes full in size and exception is throwing NSRangeException.So guys please help me.Thanks in advance.
Use following method in your code to allow zoom -
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return [self.scrollView.subviews objectAtIndex:0];
}
I'm drawing a graph on a UIView, which is contained by a UIScrollView so that the user can scroll horizontally to look around the entire graph.
Now I want to zoom the graph when a user pinches in with two fingers, but instead of zooming in a view with the same rate for X and Y direction, I want to zoom only in the X direction by changing the X scale, without changing the Y scale.
I think I have to catch the pinch in/out gesture and redraw the graph, overriding the default zooming behavior.
But is there a way to do this?
I've been having a very difficult time to catch the pinch gesture on the UIScrollView, as it cancels the touches when it starts to scroll. I want the zooming to work even after the UIScrollView cancels the touches. :(
Thanks,
Kura
Although you cannot delete the existing pinch gesture recognizer, you can disable it and then add your own:
// Disable existing recognizer
for (UIGestureRecognizer* recognizer in [_scrollView gestureRecognizers]) {
if ([recognizer isKindOfClass:[UIPinchGestureRecognizer class]]) {
[recognizer setEnabled:NO];
}
}
// Add our own
UIPinchGestureRecognizer* pinchRecognizer =
[[UIPinchGestureRecognizer alloc] initWithTarget:self
action:#selector(pinch:)];
[_scrollView addGestureRecognizer:pinchRecognizer];
[pinchRecognizer release];
Then in
- (void) pinch:(UIPinchGestureRecognizer*)recognizer { .. }
use
[recognizer locationOfTouch:0 inView:..]
[recognizer locationOfTouch:1 inView:..]
to figure out if the user is pinching horizontally or vertically.
You should instead access the gestureRecognizers (defined in UIView), there are several of them being used by the scroll view,
figure out which one is the pinch recognizer and call removeGestureRecognizer: on the scroll view, then create your own and have it do the work, add it back with addGestureRecognizer:.
these are all public API,
the recognizers and what order they are in are not (currently),
so program defensively when accessing them
(this is a perfectly valid way to manipulate UIKit views, and Apple won't/shouldn't have issues with it - though they will not guarantee it works in any future release)
You should be able to subclass UIScrollView and override the touchesBegan: method. Don't call [super touchesBegan:] but instead, adjust the zoom as you like:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
//Anything you want. Probably you would want to store all the touches
//or their values, so that you can compare them to the touches
//in the touchesEnded: method,
//thus letting you know what the pinch amount was
}
If you like, you can judge whether it's a pinch or not, and if it's not, call the super method, and only handle it yourself for custom pinches.
Edsko & bshirley answers are good, but they don't tell where to place the code.
First, I placed it in viewDidLoad method, but no Pinch Gesture Recognizer was found in the scrollview (maybe because my scrollview is an IBOutlet).
Then I tried in viewWillAppear or viewDidAppear and the UIPinchGestureRecognizer was here.
I am trying to create a small game for the iPhone with images and I want to them to zoom in when the player is pinching on the screen. I have seen the tutorials with one UIImageView. However, now that I am using multiple UIImageViews, things do not work OK.
I put them in an UIView and I am trying to zoom the UIView. However things are not scaling inside the screen when I run the simulator.
I use the following code
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return containerView; //containerView is the UIView containing all the UIIMageviews
}
-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
[containerView setTransform:CGAffineTransformIdentity];
containerView.contentScaleFactor = scale;
}
Any suggestions?
Thanx!
Have a look at the ScrollViewSuite sample on the apple developer site, that has a working example of what I think you're trying to do.
(I think I got the name right, the developer site is down for updates just now so I can't give you a link.)
Is there an "accepted" way of performing (pinch) zoom on a view that is not based on UIScrollView?
There's a code sample by Erica Sadun that does the math for treating touch events as scale/rotate/translate transforms that you can probably borrow from. Basically, it sounds like you want to apply a scaling affine transform. This code doesn't include the niceties of "bouncing" the view when you reach the edges of the content, so you'll have to do that yourself.
Full disclosure: I haven't done this in almost a year. It's likely that there are frameworks now that include much more straightforward support for this feature.
If you are working in iPhone OS 3.2 (for the iPad) or iOS 4 for the iPhone 4, you can use the UIPinchGestureRecognizer class to detect pinch gestures.
This code helps to zoom UIImageView without using UIScrollView.
-(void)HandlePinch:(UIPinchGestureRecognizer*)recognizer{
if ([recognizer state] == UIGestureRecognizerStateEnded) {
NSLog(#"=======Scale Applied===========");
if ([recognizer scale]<1.0f) {
[recognizer setScale:1.0f];
}
CGAffineTransform transform = CGAffineTransformMakeScale([recognizer scale], [recognizer scale]);
imgView.transform = transform;
}
}